Exothermic hot top insert



Oct. 18, 1966 E. F. FRANZEN EXOTHERMIC HOT TOP INSERT Filed Sept. 2, 1964 fic/1,

It /f/ f f INVENTOR.

United States Patent O 3,279,007 EXOTHERMIC HOT TOP INSERT Erwin F. Franzen, 3718 176th Place, Lansing, Ill. Filed Sept. 2, 1964, Ser. No. 393,869 6 Claims. (Cl. 22-209) 'This invention relates to improvements in the control of slidication of molten metal, and particularly to a method and apparatus for controlling, by the use of exothermic material, solidiiication of molten metal in an ingot mold under non-contaminating conditions.

Uneven cooling patterns and contaminations attributable to current hot top practice `have plagued ingot pouring operations for many years. Many variant arrangements ofthe conventional mud-coated, brick-lined hot top assemblies have `been tried, including exothermic material, but no entirely satisfactory solution has been found in the opinion of many skilled in the art. The problem of contamination by spalling of the conventional mudcoating from contact with the molten metal or exposure to the radiant heat of the pouring stream has persisted. The problem of bridging, or cross sectional solidication of the ingot in the area of the lower end of the hot top while the metal remains molten above and below this area has also persisted.

The high cost and complexity of operation inherent in present arrangements due t-o the use of supporting pegs, every heat replacement of mud or clay coating and frequent replacement of brick lining, refractory bottom rings, wiper strips and wire clips with their considerable accompanying set up time has likewise persisted.

Accordingly, a primary object of this invention is to provide a method of controlling ingot solidication whereby a desired cooling pattern and Ia sound ingot may consistently be achieved.

Another object is to provide a method of controlling ingot solidication which virtually eliminates the condition commonly referred to as bridging Yet a further object is to pr-ovide a method of controlling ingot solidification as described a'bove in which contamination which is presently inherent in many conventional hot top systems is eliminated.

Yet `a further object is to provide a hot top system which eliminates the conventional refractory bottom ring, clips, wiper strips, Wood pegs, and clay coating.

A further object is to provide a hot top assembly in which the life of the lining brick is perhaps ten times greater than the life currently obtained.

A further object is to provide a hot top system which, by eliminating rings and coatings, eliminates recognized sources of dirt and moisture.

Another object is to provide a hot topping system which provides increased tonnage yields due to exothermic feeding and the use of a hot top having a reduced height.

Yet a further object is to provide a -hot t-op assembly which is smaller in volume and weight than conventional hot tops thereby reducing shipping costs.

A further object is to provide a hot topping system which eliminates the mess presently encountered in the r'nelt shop due to breaking up large monolithic tops.

Yet a further object is to provide a hot topping system having a rapid repeat make-up time attributable to constructional simplicity, quick installation and the elimination of mudding and drying time.

Another object is to provide a hot topping system having all of the aforementioned advantages which can be employed with and efliciently iutilizes conventional hot top castings.

Other objects and advantages will become apparent from reading the following description of the invention.

The invention is illustrated more or less diagrammatically in the accompanying drawings wherein:

FIGURE l is a cross section through a hot top assembly of the present invention;

FIGURE 2 is a view taken substantially alon-g the line 2 2 of FIGURE 1;

FIGURE 3 is a cross section through another embodiment of the invention;

FIGURE 4 is a detailed view to an enlarged scale of one form of comp'artmented exothermic construction; and

FIGURE 5 is a detailed view again to a larger scale of another form of compartmented construction of exothermic material.

Like reference numerals will be used to refer to like parts throughout the following description of the drawings.

The hot top assembly of this invention is indicated generally at 10 iu FIGURES l and 2, the assembly .being shown in position on the upper end of an ingot mold 11. The hot top assembly includes a pair of castings 12 and 13 both of which may be of conventional construction. Upper castings or collar 12 includes a pair of oppositely disposed trunnions 14 and 15 adjacent the upper end of the collar. A ange 16 extends peripherally outwardly from the lower end of the collar. A corresponding peripheral liange 17 extends outwardly from the upper end of lower collar 13, flanges 16 and 17 being contoured for abutting engagement. A lip 18 extends inwardly from the lower end of collar 13.

A conventional `refractory lining is indicated at 20. The lining is composed of bricks having a composition conventionally used in existing hot topping systems. The lower course 21 of the bricks rests upon the inwardly projecting lip 18, lip 18 thereby supporting the entire refractory lining 20.

A lightweight, portable hot top 'sub-structure is indicated generally at 25. The structure includes a liner or shield means 26 which is c-omposed of a material compatible with the molten metal in the ingot mold. A sheet metal low carbon steel liner on the order of about 1/16 thickness may be employed to advantage, for example. The aforementioned dimension -is given merely by way of example and it should be understood that the thickness of the metal liner is not critical so long as it performs a protective function which will later be described in detail. The upper portion 27 of the liner ts relatively snuggly against the inner surface of the upper brick courses. The lower portion of the liner is offset as at 28. In this instance the lower end of the liner is directed outwardly, as at 29, and then inwardly as at 30, so as to pro-vide, in conjunction with the lower courses of brick, a chamber.

A layer of exothermic material is indicated at 33. The exothermic material may be self-sustaining, as by being baked into the illustrated configuration. The thickness of the exothermic material will vary from application to application depending upon the type of metal in the ingot mold, the tapping temperature, the configuration of the hot top, the desired rate of solidification and perhaps other factors. In a l7 ton conventionally shaped ingot mold a layer on t'he order of l-inch thickness may be employed to advantage.

A layer of parting compound is .indicated at 35. The parting `compound functions to prevent erosion and mutip lation of the inner faces of the brick courses due to the it is shown as formed of at sheet stock it is contemplated that other types of stock may be employed.

The exothermi-c structure is secured to the remainder of the hot top assembly by upper tabs 36-39 and lower tabs 40-43. The upper tabs may be of relatively light weight since they merely serve to support unit 25 from the collars 12 and 13. The lower tabs are preferably of considerably heavier stock since they function to support the Weight of the entire hot top assembly from the upper face 45 of the ingot mold until the time when molten metal has reached a level at which the hot top will oat on it.

Another embodiment is illustrated in FIGURE 3. In this embodiment the exothermic material has been formed into two shapes, a tubular, upright, portion 48 and a lower, horizontally axised ring portion 49. Tubular section 48 may be formed of a compartmented construction, two typical examples of which are indicated in FIGURES 4 and 5.

In FIGURE 4, the compartmented section includes side walls 50 and 51each of which may be composed of cardboard, and a inner serpentine shaped compartment forming Wall 52, which also may be made of cardboard. The serpentine wall may be secured to the planar side walls at the points of contact 53, 54 and 55 by any suitable adhesive well-known in the cardboard art. It is not necessary that the adhesive or the cardboard be heat resistant since the only function of the walls is to serve as a package for the loose exothermic material 56 during shipment. Once the tubular section 48 is placed in position in a hot top assembly the surrounding components will maintain it in place.

In FIGURE S a honeycomb construction is illustrated. This construction is formed by the planar side walls 57, 5S, and the perpendicularly bent inner Wall 59.

The use and operation of the invention is as follows:

The exothermic material 33 may be baked in place against the sheet metal liner 25 at the hot top structure fabrication plant. This unit may then be shipped to the ultimate consumer, generally a melt shop. Depending upon the thickness of the offset 32, it may be possible to stack a number of units one atop the other thereby considerably reducing shipping costs. The melt shop user then installs the hot top unit in the hot top assembly by means of strip steel tabs 36-39. A layer of parting compounding 35 may or may not be employed depending upon conditions in the melt shop. The entire assembly is then supported from the upper end of the empty ingot mold by the bottom tabs 40-43.`

Molten metal is tapped into the hot topped mold up to level 60 of FIGURE l. During tapping the two upper coursesV of bricks will not be directly exposed to the radiant heat of the pouring stream because of the nterposition of liner 26 between the stream and lining. As a result spalling and moisture migration into the pouring stream is 4completely eliminated. This shielding of the brick has the further advantage that brick lining life is materially lengthened. It is contemplated that the life may be perhaps ten times greater than the life of a conventional unprotected lining. Further, the conventional refractory lining or mudding has been eliminated. It is well known in the industry that spalling of the mud or clay coating is a source of contamination and moisture.

As the metal rises within the lower portion 28 of the metal liner, the liner is heated to a temperature sufficient to ignite the exothermic material. As the exothermic material bums it gives off heat Vat a rate suflicient to slow the cooling of the upper end of the ingot until solidification has progressed uniformally upwardly, and the pipe will therefore be fed -by a reservoir of hot metal enclosed within liner` 28. Preferably the thickness of the liner is so selected that it will remain in an unmelted condition at least until the time at which the danger of bridging is avoided and solidication has progressed to the lower. end of the hot top'. The liner may be softened to a condition in which it merely forms a crust or a stili slush but it should not melt away completely and thereby permit the exothermic material to migrate into the liquid metal reservoir.

Alternately, in lieu of the self sustaining baked in place layer of exothermic material 33, the variations of FIG- URES 4 and 5 may be employed. In this event the cardboard liners which contain loose exothermic material 56 may be shipped separately to the melt shop and quickly assembled just prior to use.

In any event, once a hot top has been removed the upper connecting tabs 36 are released and the used liner and hot top material removed from the hot top. If a layer of parting Icompound 35 has been employed the lower courses of brick will be in a virtually undeteriorated condition. The metal collars 12 `and 13 and brick lining 20 may then be immediately used aga-in without any further make ready other than slipping in and connecting a hot top unit V10.

Although several embodiments of the .invention have been illustrated and described it will at once be apparent to those skilled in the art that variations may be made within the spirit of the invention. Accordingly it is intended that the scope of the invention be limited not by the foregoing exemplary description but solely by lthe scope of the hereinafter appended claims when interpreted in light of pertinent prior art.

1. A hot top insert, said insert including generally vertically oriented shield means composed of a metallic material compatible with the molten metal with which said shield means will come in contact, andV exothermi-c material disposed behind the shield means and in heat conductive relationship therewith for ignition by heat from the molten metal transmitted through the shield means,

said exothermic material being disposed continuously` about the external periphery of the shield means, the shield means and exothermic material forming an enclosure into which molten metal may be received to a substantial depth,

said metallic shield means and exothermic material ex-I` y tending generally radially outwardly from, and continuously about, the lower portion thereof whereby the shield means, and thereby the heat generated from the exothermic material, is exposed rto the molten metal in at least two planes,

`said generally radially outwardly disposed portionof the shield means and exothermic material extending outwardly a distance sufficient to closely conform the internal periphery of the mold structure which is adapted for use with said hot top insert.

2. The combination of a hot top,

said hot top having a refractory lining, and

a hot top insert, said insert including a metallic shield means composed of a metal compatible which will come in contact with the with the metal insert,

a layer of exothermic material disposed between the` 3. The combination of claim 2 further characterized in that a peripheral portion of the shield means and exothermic 5 6 material extends generally radially outwardly from tially self supporting interior compartmented construc-A the lower portion thereof whereby the shield means tion within which the eXothermic material is received. and the heat generated from the exothermic material is exposed to the molten metal in at least two planes. References Cited by the EXamllel 4. The combination of claim 2 further characterized 5 UNITED STATES PATENTS in that the exothermic material is carried by a container contoured to lay against the exterior of the shield means 2913786 11/1959 Farnsworth et al' 249-200 X in heat conductive relationship therewith. ggf/Her 249 5. The combination of clalm 4 further characterized 3,183,562 5/1965 Moore n 22 1 in that the exothermic material is carried by the container 10 in a substantially non-self-supporting condition.

6. The combination of claim 4 further characterized I' SPENCER OVERHOLSER Primary Exammer' in that the exothermic material container has a substan- E- MAR, Assistant Examiner- 

2. THE COMBINATION OF A HOT TOP, SAID HOT TOP HAVING A REFRACTORY LINING, AND A HOT TOP INSERT, SAID INSERT INCLUDING A METALLIC SHIELD MEANS COMPOSED OF A METAL COMPATIBLE WITH THE METAL WHICH WILL COME IN CONTACT WITH THE INSERT, A LAYER OF EXOTHERMIC MATERIAL DISPOSED BETWEEN THE LOWER PORTION OF THE REFRACTORY LINING AND THE SHIELD MEANS, THE UPPER EDGE OF SAID LAYER OF EXOTHERMIC MATERIAL TERMINATING INTERMEDIATE THE UPPER AND LOWER ENDS OF THE SHIELD MEANS, SAID SHIELD MEANS OVERLYING THE EXOTHERMIC MATERIAL AND THE ENTIRE PORTION OF THE REFRACTORY LINING WHICH IS ABOVE THE UPPER EDGE OF THE EXOTHERMIC MATERIAL TO THEREBY SHIELD THE REFRACTORY LINING FROM THE HEAT EVOLVED FROM THE MOLTEN TAPPED METAL PASSING THROUGH THE HOT TOP. 